WASHINGTON (AP) — Get ready to find out who the millionaires are behind this year’s presidential election. Shadowy outside groups funded by anonymous donors and working on behalf of candidates they support have pummeled Mitt Romney, Newt Gingrich and others for the past two months by spending millions of dollars on mostly negative […]

WASHINGTON (AP) — Get ready to find out who the millionaires are behind this year’s presidential election.

Shadowy outside groups funded by anonymous donors and working on behalf of candidates they support have pummeled Mitt Romney, Newt Gingrich and others for the past two months by spending millions of dollars on mostly negative TV ads that have had an enormous impact on the fight for the Republican presidential nomination.

Now, for the first time since they started shaping this campaign in earnest, many of those “super” political action committees are set to disclose just who is financing their pseudo-campaign operations. Many took advantage of a change in federal rules that essentially let them shield their donors’ identities until after key primary elections in January. But they still must submit their financial reports to the Federal Election Commission by Tuesday.

Only a handful of donors are known, including Las Vegas billionaire casino owner Sheldon Adelson. His two checks for $5 million apiece to Winning Our Future, a pro-Gingrich group, essentially kept the former House speaker’s White House campaign afloat at critical junctures just before the South Carolina and Florida primaries.

Bain Capital executives and Romney friends have lined the bank accounts of the pro-Romney group Restore Our Future. Former Bain executive Edward Conrad donated $1 million last spring and Marriott International Inc. CEO J.W. Marriott Jr. gave the group $500,000, seed money spent to successfully hammer Gingrich in Iowa late last year as he started to rise.

That’s when the super PACs sprang into action in full force.

Since then, groups working on behalf of Republican candidates for president have spent roughly $25 million in TV ads, most of which have been negative, in the first four states to vote in the GOP nomination battle — Iowa, New Hampshire, South Carolina and Florida.

Of that, the pro-Romney Restore Our Future has spent about $14 million on ads, mostly to take down Gingrich in Iowa and Florida. That’s more than the roughly $12 million Romney himself has spent on TV ads.

The super PACs have also unleashed millions on expenses typically reserved for campaigns, including direct mailings, phone calls and get-out-the-vote efforts.

It’s a precursor to the general election, when super PACs aligned with both Republicans and President Barack Obama are planning to dole out even larger sums.

These groups are the products of a 2010 Supreme Court ruling that stripped away old restrictions on corporate and union spending in federal elections. They can’t directly coordinate with the candidates they support, but many are staffed with former campaign workers who have an intimate knowledge of their favored candidate’s strategy.

Some donors will never be known because some super PACs have established not-for-profit arms that can shield contributors’ identities. Those arms can spend more than roughly half of their money on so-called advocacy, although campaign-finance reformers have urged the Internal Revenue Service to reduce that share.

Super PACs like American Crossroads — backed by George W. Bush political adviser Karl Rove — and its own nonprofit arm played a significant role in the 2010 midterm elections, helping deliver the House to the GOP and boost the number of Republicans in the Senate.

Tuesday’s filings to the FEC won’t just reveal many of the committees’ financial backers; they’ll also show how their money is being spent, particularly on infrastructure, payroll and travel. The same will be true in the campaign financial filings for President Barack Obama, Romney, Gingrich and others, who last released their finances in October 2011.

But, above all, the FEC filings are likely to show the awesome impact super PACs have in supplementing expansive, national campaigns.

Super PACs have become headaches for campaign-finance watchdogs, who have long warned of a potentially corruptive influence that hasn’t been seen since the days of Watergate.

But some GOP-leaning groups say their ads contribute to a marketplace of ideas and counterbalance the huge sums of cash that Obama and the Democratic National Committee plan to spend on the president’s re-election bid.

By law, presidential campaigns can raise, at most, $5,000 total from an individual donor.

But super PACs can solicit and spend unlimited money — and some employ affiliated groups, known as 501(c)4 organizations, whose donors are allowed to remain anonymous. Watchdog groups like Democracy 21 have complained to federal regulators on that front, asking the IRS to limit how much those nonprofit groups can spend on political advocacy.

Think about who gets rich off of the Venezuela regime-change agenda. It’s the same people that said we had to invade Iraq in order to prevent nuclear apocalypse. It’s the same people who said the world would stop turning on its axis if we didn’t carpet bomb Libya and Syria.